1. Field of the Invention
The present invention relates to methods for testing ejection, printing apparatuses, methods for forming ejection-test patterns, ejection-test patterns, computer-readable media, and printing systems.
2. Description of the Related Art
Inkjet printers are known as a type of printing apparatus that carries out printing by ejecting ink onto various media such as paper, cloth, and film. These inkjet printers perform color printing by ejecting color inks such as cyan (C), magenta (M), yellow (Y), and black (K) to form dots on the medium. Ink ejection is normally carried out using nozzles.
However, depending on such factors as firm fixing of the ink, a nozzle may sometimes become clogged and ink may not be properly ejected. When ink is not properly ejected from the nozzles, dots cannot be formed on the medium, and it is not possible to form a proper image. Therefore, it is necessary to test whether or not ink is being ejected properly by periodically testing nozzle ejection in order to find such nozzle ejection failure.
For this reason, it has been conventionally proposed that in serial-type printers such as inkjet printers, tests on whether or not there are defective dots are to be performed by actually carrying out printing on a recording paper (see JP 11-240191A). In this case, an image sensor is provided in the printer, and this image sensor is used to check whether or not there are defective dots by detecting the state of the printing. When there is a defective dot, the position of the defective dot is stored, and this dot is complemented during printing by using another nozzle, for example.
In recent years, printing apparatuses have been introduced in which a colorless transparent liquid called “clear ink” is ejected in addition to the color inks such as cyan (C), magenta (M), yellow (Y), and black (K). The clear ink ejected in such cases is a liquid that is ejected for the purpose of, for example, improving the quality of the printed image, and specifically, it plays: (1) the role of causing the ink to coagulate and promote fixation, (2) the role of improving the level of gloss, and (3) the role of forming a protective layer on the surface of the medium.
However, since such clear ink is colorless and transparent, it cannot be easily detected by a sensor or the like when ejected onto the medium, and for this reason, it is difficult to carry out ejection tests by forming test patterns on the medium in the same way as for color inks.